U.S. patent number 11,452,255 [Application Number 16/432,039] was granted by the patent office on 2022-09-27 for work vehicle.
This patent grant is currently assigned to Kubota Corporation. The grantee listed for this patent is Kubota Corporation. Invention is credited to Hitoshi Aoyama, Kanako Komori, Takeshi Komorida, Kentaro Shinkai, Kensuke Uemoto, Katsuhiko Uemura, Hideya Umemoto, Shinichi Yamada.
United States Patent |
11,452,255 |
Umemoto , et al. |
September 27, 2022 |
Work vehicle
Abstract
A work vehicle that performs an operation while traveling
autonomously includes: a base frame configured to support a wheel;
a unit frame configured to support an operation unit that performs
the operation; a link frame capable of changing a relative height
of the unit frame with respect to the base frame, the link frame
spanning between the base frame and the unit frame; and a setting
unit configured to set an operating height of the operation unit
with respect to a working surface of a working field in which the
operation is performed, in accordance with operation information
indicating an operation target to be subjected to the
operation.
Inventors: |
Umemoto; Hideya (Sakai,
JP), Aoyama; Hitoshi (Sakai, JP), Uemura;
Katsuhiko (Sakai, JP), Komorida; Takeshi (Sakai,
JP), Uemoto; Kensuke (Sakai, JP), Shinkai;
Kentaro (Sakai, JP), Yamada; Shinichi (Sakai,
JP), Komori; Kanako (Sakai, JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
Kubota Corporation |
Osaka |
N/A |
JP |
|
|
Assignee: |
Kubota Corporation (Osaka,
JP)
|
Family
ID: |
1000006587072 |
Appl.
No.: |
16/432,039 |
Filed: |
June 5, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190387671 A1 |
Dec 26, 2019 |
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Foreign Application Priority Data
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Jun 21, 2018 [JP] |
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JP2018-118112 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G05D
1/0212 (20130101); A01D 34/74 (20130101); A01D
34/64 (20130101); G05D 1/0088 (20130101); A01D
34/008 (20130101); A01D 2101/00 (20130101); G05D
2201/0208 (20130101) |
Current International
Class: |
A01D
34/00 (20060101); G05D 1/00 (20060101); G05D
1/02 (20200101); A01D 34/74 (20060101); A01D
34/64 (20060101) |
Field of
Search: |
;701/28 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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1532856 |
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May 2005 |
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EP |
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3225094 |
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Oct 2017 |
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EP |
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2532592 |
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May 2016 |
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GB |
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56134130 |
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Oct 1981 |
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JP |
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5284806 |
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Nov 1993 |
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JP |
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2013164741 |
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Aug 2013 |
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JP |
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2017112927 |
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Jun 2017 |
|
JP |
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2017176117 |
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Oct 2017 |
|
JP |
|
Primary Examiner: Shafi; Muhammad
Attorney, Agent or Firm: The Webb Law Firm
Claims
The invention claimed is:
1. A work vehicle that performs an operation while traveling
autonomously, comprising: a base frame configured to support a
wheel; a unit frame configured to support an operation unit that
performs the operation; a link frame capable of changing a relative
height of the unit frame with respect to the base frame, the link
frame spanning between the base frame and the unit frame; a setting
unit configured to set an operating height of the operation unit
with respect to a working surface of a working field in which the
operation is performed, in accordance with operation information
indicating an operation target to be subjected to the operation; a
working field map acquisition unit configured to acquire a map
illustrating the working field; a path information acquisition unit
configured to acquire traveling path information indicating a
traveling path during the operation; and a determination unit
configured to determine whether or not a current location is in an
area where the lawn grass has been cut based on the map and the
traveling path information, wherein: the operation is a lawn mowing
operation to cut lawn grass growing on the working field, the work
vehicle further comprises an evaluation unit configured to evaluate
a grass height of the lawn grass and a grass density of the lawn
grass, the setting unit sets the operating height in accordance
with a result of the evaluation performed by the evaluation unit,
and the evaluation unit evaluates the grass height and the grass
density based on a result of the determination performed by the
determination unit.
2. The work vehicle according to claim 1, further comprising: a
captured image acquisition unit configured to acquire a captured
image obtained by capturing an image of the working field, wherein
the evaluation unit evaluates the grass height and the grass
density based on the captured image.
3. A work vehicle that performs an operation while traveling
autonomously, comprising: a base frame configured to support a
wheel; a unit frame configured to support an operation unit that
performs the operation; a link frame capable of changing a relative
height of the unit frame with respect to the base frame, the link
frame spanning between the base frame and the unit frame; a setting
unit configured to set an operating height of the operation unit
with respect to a working surface of a working field in which the
operation is performed, in accordance with operation information
indicating an operation target to be subjected to the operation; a
load sensor configured to detect a load; and a control unit
configured to, if the load sensor detects a load that is greater
than or equal to a preset value, stop running the operation unit
and roll the wheel in a direction opposite to a direction in which
the wheel was rolling when the load sensor detected the load that
is greater than or equal to the preset value.
4. The work vehicle according to claim 3, further comprising: a
bumper member to which the load sensor is attached, the bumper
member being supported by the base frame so as to at least surround
the operation unit and the wheel, wherein the bumper member is
configured to be in a state of surrounding the operation unit and
the wheel even if a height of the unit frame with respect to the
base frame is charged.
5. A work vehicle that performs an operation while traveling
autonomously, comprising: an operation unit configured to perform
the operation, the operation unit being mounted in a vehicle body:
a load calculation unit configured to calculate a load of the
operation, the load calculation unit being provided forward of the
operation unit relative to the traveling direction in the vehicle
body; and a decision unit configured to decide whether to drive
both the load reduction unit and the operation completion unit or
to only drive the operation completion unit, based on a result of
the calculation performed by the load calculation unit, wherein the
operation unit includes a load reduction unit configured to perform
an operation for reducing a load of the operation whose load is
greater than a preset load, and an operation completion unit
configured to perform an operation, which is the remainder of the
operation, for which the load reduction unit has reduced the
load.
6. The work vehicle according to claim 5, wherein: the load
reduction unit is provided in a front portion of the vehicle body
relative to a traveling direction, and the operation completion
unit is provided in a rear portion of the vehicle body relative to
the traveling direction.
7. The work vehicle according to claim 5, wherein: the operation
completion unit is provided in a center portion of the vehicle body
as viewed from above, and the load reduction unit is provided so as
to surround the operation completion unit in the vehicle body as
viewed from above.
8. The work vehicle according to claim 5, further comprising: a
load calculation unit configured to calculate a load of the
operation, the load calculation unit being provided forward of the
operation unit relative to the traveling direction in the vehicle
body; and a decision unit configured to decide whether to drive
both the load reduction unit and the operation completion unit or
to only drive the operation completion unit, based on a result of
the calculation performed by the load calculation unit.
9. The work vehicle according to claim 5, wherein: the operation
unit is driven by a motor that is supplied with electric power from
a battery mounted in the vehicle body, and the decision unit
decides a running state of the operation unit also using a cost
required to complete the operation, the cost being calculated based
on at least one of time required for an operation that was
previously performed in the same working field, the number of times
that the battery was charged, and power consumption required for
the operation.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority to Japanese Patent Applications
Nos. 2018-118112 and 2018-118113 filed Jun. 21, 2018, the
disclosures of which are hereby incorporated by reference in their
entirety.
TECHNICAL FIELD
The present invention relates to a work vehicle that performs an
operation while traveling autonomously.
BACKGROUND ART
Conventionally, a technology for causing a vehicle to travel
autonomously has been used. Examples of such a vehicle that travels
autonomously include a work vehicle that travels autonomously while
performing a predetermined operation (e.g. lawn mowing) in a large
field. JP 2013-164741 A describes an example of this kind of
technology.
An unmanned travel work vehicle described in JP 2013-164741 A
includes an electric motor that is mounted in a vehicle body and is
supplied with power from a battery, and a running motor that is
mounted in the vehicle body. This unmanned travel work vehicle
performs an operation by driving an operation machine mounted in
the vehicle body using the electric motor, while driving wheels
using the running motor and traveling in a working area.
Conventionally, a technology for causing a vehicle to travel
autonomously has been used. Examples of such a vehicle that travels
autonomously include a work vehicle that travels unmanned while
performing a predetermined operation (e.g. lawn mowing) in a large
field. JP 2013-164741A describes an example of a technology related
to such a work vehicle.
An unmanned travel work vehicle described in JP 2013-164741A
includes an electric motor that is mounted in a vehicle body and is
supplied with power from a battery, and a running motor that is
mounted in the vehicle body. This unmanned travel work vehicle
performs an operation by driving an operation machine mounted in
the vehicle body using the electric motor, while driving wheels
using the running motor and traveling in a working area.
SUMMARY
A problem corresponding to the background art [1] is as
follows.
As mentioned above, the technology described in JP 2013-164741A is
for performing an operation while driving an operation machine
mounted in the vehicle body. However, in the case where, for
example, the operation is a mowing operation as described in Patent
JP 2013-164741A, the degree of growth of grass may differ depending
on the season. The greater the grass height, the heavier the
working load, and thus the operation cannot be performed smoothly
in some cases. Moreover, if the required mowing height differs
between working fields, a user needs to adjust the mowing height
when necessary.
Thus there is a demand for a work vehicle capable of automatically
changing the operating height, i.e. the height at which the
operation is performed, in accordance with an operation target.
A problem corresponding to the background art [2] is as
follows.
As mentioned above, the technology described in JP 2013-164741A is
for performing an operation while driving the operation machine
mounted in the vehicle body. However, in the case where, for
example, the operation is a mowing operation as described in JP
2013-164741A, the degree of growth of grass may differ even between
different locations within a single working field. For this reason,
the grass height and the grass density in a single working field
are not necessarily uniform. Then the technology described in JP
2013-164741A may not enable the operation to be performed smoothly
if the grass height and/or the grass density is not uniform.
There is a demand for a work vehicle capable of smoothly performing
the operation thereof.
A means for solving the problem [1] is as follows.
A characteristic configuration of a work vehicle according to an
aspect of the present invention lies in a work vehicle that
performs an operation while traveling autonomously, including: a
base frame configured to support a wheel; a unit frame configured
to support an operation unit that performs the operation; a link
frame capable of changing a relative height of the unit frame with
respect to the base frame, the link frame spanning between the base
frame and the unit frame; and a setting unit configured to set an
operating height of the operation unit with respect to a working
surface of a working field in which the operation is performed, in
accordance with operation information indicating an operation
target to be subjected to the operation.
With this characteristic configuration, the operating height can be
automatically changed in accordance with operation information.
Accordingly, a plurality of operations to be performed at different
operating heights can also be adapted to.
Also, it is preferable that the operation is a lawn mowing
operation to cut lawn grass growing on the working field; the work
vehicle further includes an evaluation unit configured to evaluate
a grass height of the lawn grass and a grass density of the lawn
grass; and the setting unit sets the operating height in accordance
with a result of the evaluation performed by the evaluation
unit.
With this configuration, the operating height can be changed in
accordance with the grass height and the grass density of lawn
grass. Also, a mowing operation can be performed at separate times
depending on the grass height and the grass density of lawn grass.
Thus the load on the operation unit can be reduced. Accordingly, it
is also possible to reduce the size of the operation unit and
reduce the output required (i.e. reduce the horsepower
required).
Also, it is preferable that the work vehicle further includes a
captured image acquisition unit configured to acquire a captured
image obtained by capturing an image of the working field, wherein
the evaluation unit evaluates the grass height and the grass
density based on the captured image.
With this configuration, the grass height and the grass density of
lawn grass can be recognized from a captured image, and then the
operating height can be changed. Thus, this configuration can also
reduce the load on the operation unit. As a result, it is possible
to reduce the size of the operation unit and reduce the output
required (i.e. reduce the horsepower required).
Also, it is preferable that the work vehicle further includes a
working field map acquisition unit configured to acquire a map
illustrating the working field; a path information acquisition unit
configured to acquire traveling path information indicating a
traveling path during the operation; and a determination unit
configured to determine whether or not a current location is in an
area where the lawn grass has been cut, based on the map and the
traveling path information, wherein the evaluation unit evaluates
the grass height and the grass density based on a result of the
determination performed by the determination unit.
With this configuration, the grass height and the grass density of
lawn grass can be recognized from a movement trajectory of the work
vehicle, and then the operating height can be changed. Thus, this
configuration can also reduce the load on the operation unit. As a
result, it is possible to reduce the size of the operation unit and
reduce the output required (i.e. reduce the horsepower
required).
Also, it is preferable that the work vehicle further includes a
load sensor configured to detect a load; and a bumper member to
which the load sensor is attached, the bumper member being
supported by the base frame so as to at least surround the
operation unit and the wheel, wherein the bumper member is
configured to be in a state of surrounding the operation unit and
the wheel even if a height of the unit frame with respect to the
base frame is changed.
With this configuration, even if the operating height has been
changed, the gap between the bumper member and the working surface
can be kept fixed (i.e. an unnecessarily large gap can be prevented
from being formed between the bumper member and the working
surface). Accordingly, a user can be prevented from accidentally
inserting a hand or a foot into the operation unit and getting
injured.
Also, it is preferable that the work vehicle further includes a
control unit configured to, if the load sensor detects a load that
is greater than or equal to a preset value, stop running the
operation unit and roll the wheel in a direction opposite to a
direction in which the wheel was rolling when the load sensor
detected the load that is greater than or equal to the preset
value.
With this configuration, if the load sensor detects a load that is
greater than or equal to the preset value, the driving of the
operation unit can be stopped, and the work vehicle can be caused
to travel in a direction opposite to the direction in which the
work vehicle has been traveling thus far. Accordingly, even if a
person approaches the work vehicle, the person can be prevented
from getting injured.
A means for solving the problem [2] is as follows.
A characteristic configuration of a work vehicle according to an
aspect of the present invention lies in a work vehicle that
performs an operation while traveling autonomously, including: an
operation unit configured to perform the operation, the operation
unit being mounted in a vehicle body, wherein the operation unit
includes a load reduction unit configured to perform an operation
for reducing a load of the operation whose load is greater than a
preset load, and an operation completion unit configured to perform
an operation, which is the remainder of the operation, for which
the load reduction unit has reduced the load.
With this characteristic configuration, an operation can be
completed by first performing the operation using the load
reduction unit to reduce the load, and then performing the
remainder of the operation using the operation completion unit.
Accordingly, the load on the operation unit can be reduced compared
with the case where these operations are performed all at once. As
a result, the time required for the operation can be shortened, and
the operation can be performed smoothly. In addition, the operation
unit can also be prevented from deteriorating or getting
damaged.
Also, it is preferable that the load reduction unit is provided in
a front portion of the vehicle body relative to a traveling
direction, and the operation completion unit is provided in a rear
portion of the vehicle body relative to the traveling
direction.
With this configuration, the load can be automatically shared
between the load reduction unit and the operation completion unit
in accordance with the traveling of the work vehicle.
Also, it is preferable that the operation completion unit is
provided in a center portion of the vehicle body as viewed from
above, and the load reduction unit is provided so as to surround
the operation completion unit in the vehicle body as viewed from
above.
With this configuration as well, the work vehicle can complete the
operation while appropriately traveling autonomously.
Also, it is preferable that the work vehicle further includes a
load calculation unit configured to calculate a load of the
operation, the load calculation unit being provided forward of the
operation unit relative to the traveling direction in the vehicle
body; and a decision unit configured to decide whether to drive
both the load reduction unit and the operation completion unit or
to only drive the operation completion unit, based on a result of
the calculation performed by the load calculation unit.
With this configuration, the driving of the operation unit can be
controlled in accordance with the load. Thus energy can be
saved.
Also, it is preferable that the operation unit is driven by a motor
that is supplied with electric power from a battery mounted in the
vehicle body, and the decision unit decides a running state of the
operation unit also using a cost required to complete the
operation, the cost being calculated based on at least one of time
required for an operation that was previously performed in the same
working field, the number of times that the battery was charged,
and power consumption required for the operation.
With this configuration, the operation can be optimized, and the
running cost can be suppressed.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 illustrates a first embodiment (the same applies to FIGS. 2
to 5), and is a side view of a work vehicle;
FIG. 2 is a plan view of the work vehicle;
FIG. 3 is a structural diagram illustrating a structure of the work
vehicle;
FIG. 4 is a block diagram that schematically illustrates functional
units of the work vehicle;
FIG. 5 illustrates operating height settings;
FIG. 6 illustrates a second embodiment (the same applies to FIGS. 7
and 8), and is a side view of a work vehicle;
FIG. 7 is a plan view of the work vehicle; and
FIG. 8 is a plan view of a work vehicle according to a
variation.
BEST MODE FOR CARRYING OUT THE INVENTION
First Embodiment
The first embodiment of the present invention will be described
below.
The work vehicle according to the present invention is configured
to be able to automatically change the operating height, i.e. the
height at which an operation is performed, in accordance with an
operation target. The work vehicle performs the operation while
traveling autonomously, and the following description will take a
mowing operation to mow grass that is growing in a working field as
an example of the operation performed by the work vehicle. Here,
"autonomous traveling" according to this embodiment refers to
traveling while avoiding objects (e.g. obstacles) along a traveling
path that is set based on the output of a device mounted in the
work vehicle (e.g. output of a sensor, an image captured by a
camera etc.). Such a work vehicle corresponds to a so-called
autonomous robot.
FIG. 1 is a side view of a work vehicle 1 according to this
embodiment, and FIG. 2 is a plan view of the work vehicle 1. As
shown in FIGS. 1 and 2, the work vehicle 1 includes wheels 2 and a
body 3 (an example of a vehicle body). The wheels 2 include first
wheels 2A on one end side of the vehicle body in the
vehicle-lengthwise direction, and second wheels 2B on the other end
side in the vehicle-lengthwise direction. A pair of left and right
first wheels 2A and a pair of left and right second wheels 2B are
provided, respectively in the vehicle-widthwise direction. In this
embodiment, the first wheels 2A are provided on the rear side of
the work vehicle 1 relative to the traveling direction. The first
wheels 2A are configured as wheels that are driven and steered. The
first wheels 2A are driven by a later-described traveling control
apparatus 10. The second wheels 2B are provided on the front side
of the work vehicle 1 relative to the traveling direction. The
second wheels 2B are configured as so-called caster wheels. With
this configuration, if the left and right first wheels 2A are
rolling in the same direction at the same speed, the work vehicle 1
travels straight. If the left and right first wheels 2A are rolling
in the same direction at different speeds, the work vehicle 1 is in
a state of being steered toward the side of one of the left and
right first wheels 2A that is rolling at a lower speed.
Furthermore, if the left and right first wheels 2A are rolling in
different directions at the same speed, the work vehicle 1 can
rotate on the spot. Although, in the above description, a pair of
left and right first wheels 2A and a pair of left and right second
wheels 2B are provided, respectively in the vehicle-widthwise
direction, this is merely an example. For example, the number of
first wheels 2A may differ from the number of second wheels 2B, or
the number of first wheels 2A and the number of second wheels 2B
may be one or three or more, in accordance with the size of the
vehicle body.
The body 3 is provided with a pair of motors 4, which serve as
motive power sources for the first wheels 2A, a battery 5 for
storing electric power and supplying electric power to the motors 4
and electrical devices that the work vehicle 1 has, a traveling
control apparatus 10 for controlling the traveling of the work
vehicle 1, and a motor 6 for driving a lawn mowing apparatus 53 (an
example of an operation unit), which has a mowing blade 54, which
is used in a lawn mowing operation. The motor 6 is driven by
electric power supplied by the battery 5.
The body 3 is also provided with a satellite positioning module 99,
which is configured as a GNSS module. The satellite positioning
module 99 has a satellite antenna for receiving a GPS signal or a
GNSS signal ("GPS signal" in this embodiment). Note that the
satellite positioning module 99 may include an inertial navigation
module that incorporates a gyro-acceleration sensor and/or a
magnetic direction sensor to complement satellite navigation.
Needless to say, the inertial navigation module may be provided at
a location separate from the satellite positioning module 99. The
GPS signal acquired by the satellite positioning module 99 is used
in the aforementioned autonomous traveling of the work vehicle 1,
and also serves as "position information obtained by a GPS" and is
used by later-described functional units.
FIG. 3 is a structural diagram that more specifically illustrates a
structure of the work vehicle 1. FIG. 4 is a block diagram that
schematically illustrates functional units of the work vehicle 1.
As shown in FIGS. 3 and 4, the work vehicle 1 includes a base frame
21, a unit frame 22, link frames 23, a setting unit 24, an
evaluation unit 25, a captured image acquisition unit 26, a working
field map acquisition unit 27, a path information acquisition unit
28, a determination unit 29, load sensors 30, bumper members 31,
and a control unit 32.
The base frame 21 supports the wheels 2. As mentioned above, the
wheels 2 include a pair of first wheels 2A and a pair of second
wheels 2B. Accordingly, the base frame 21 supports the pair of
first wheels 2A and the pair of second wheels 2B. It is favorable
that the base frame 21 is configured to support rotary shafts of
the pair of first wheels 2A and the pair of second wheels 2B.
The unit frame 22 supports the lawn mowing apparatus 53. In this
embodiment, the mowing blade 54 is provided in a state of opposing
a working surface in a portion of the lawn mowing apparatus 53 on
one side in the vertical direction. Accordingly, the lawn mowing
apparatus 53 is supported by the unit frame 22 from the other side
in the vertical direction.
The link frames 23 span between the base frame 21 and the unit
frame 22. The link frames 23 are provided so as to be able to
change the relative height of the unit frame 22 with respect to the
base frame 21. Note that "to span between the base frame 21 and the
unit frame 22" means that one end portion of each link frame 23 is
fixed to the base frame 21, and the other end portion of each link
frame 23 is fixed to the unit frame 22. It is favorable that these
link frames 23 are constituted by stretchable dampers. The relative
height of the unit frame 22 with respect to the base frame 21 can
be changed due to the dampers stretching or contracting.
The setting unit 24 sets the operating height of the lawn mowing
apparatus 53 with respect to the working surface of a working field
in which the operation is performed, in accordance with operation
information, which indicates an operation target that is to be
subjected to the operation. In this embodiment, the operation
target that is to be subjected to the operation is lawn grass. The
operation information is information that indicates the state of
the lawn grass. The state of the lawn grass is information that
indicates a grass height and/or a grass density of the lawn grass.
The working surface of the working field in which the operation is
performed is a surface on which lawn grass is growing, of the
working field in which the lawn mowing operation is performed. A
surface with which the wheels 2 of the work vehicle 1 come into
contact corresponds to the working surface of the working field in
which the operation is performed. The operating height of the lawn
mowing apparatus 53 is the height at which the lawn mowing
operation is performed, and means, specifically, the height of the
mowing blade 54. Accordingly, the setting unit 24 sets the height
of the mowing blade 54 of the lawn mowing apparatus 53 with respect
to the surface with which the wheels 2 of the work vehicle 1 come
into contact, in accordance with information that indicates the
grass height and/or grass density of the lawn grass.
In this embodiment, the work vehicle 1 is provided with a camera
(not shown) for capturing an image of the front side of the working
field relative to the traveling direction of the work vehicle 1.
The captured image acquisition unit 26 acquires a captured image
obtained as a result of the camera capturing an image of the
working field. The captured image acquired by the captured image
acquisition unit 26 is transferred to the later-described
evaluation unit 25.
The evaluation unit 25 evaluates the grass height and the grass
density of lawn grass based on the captured image transferred from
the captured image acquisition unit 26. Specifically, the
evaluation unit 25 performs image recognition processing on the
captured image, and evaluates (calculates) the grass height and the
grass density of lawn grass that is included in the captured image.
The result of the evaluation performed by the evaluation unit 25 is
transferred to the aforementioned setting unit 24.
The setting unit 24 sets the height of the mowing blade 54 of the
lawn mowing apparatus 53 based on the evaluation result from the
evaluation unit 25. Specifically, as shown in FIG. 5, the operating
height is set to a predetermined first height if the grass height
of the lawn grass is less than or equal to a predetermined value
and the grass density is less than or equal to a predetermined
value (level 1), for example. Also, for example, the operating
height is set to a second height, which is greater than the first
height, if the grass height of the lawn grass exceeds the
predetermined value but the grass density is smaller than or equal
to the predetermined value (level 2). Also, for example, the
operating height is set to the first height if the grass height of
the lawn grass is less than or equal to the predetermined value but
the grass density exceeds the predetermined value (level 3). Also,
for example, the operating height is set to the second height if
the grass height of the lawn grass exceeds the predetermined value
and the grass density exceeds the predetermined value (level 4). It
is favorable that the setting unit 24 sets the operating height in
this manner.
Thus, the work vehicle 1 can automatically set the height of the
mowing blade 54 with respect to the working surface. Specifically,
it is favorable that the setting unit 24 is configured to be able
to increase or reduce the operating height of the lawn mowing
apparatus 53 using a stepper motor in accordance with the
aforementioned operating height. Needless to say, the setting unit
24 can alternatively be configured to be able to continuously
increase or reduce the operating height using a compressor and an
air bag.
The working field map acquisition unit 27 acquires a map that
illustrates the working field. The working field is set by the user
before the lawn mowing operation is performed. The working field
map acquisition unit 27 acquires the map that is set by the user
and illustrates the working field.
The path information acquisition unit 28 acquires traveling path
information, which indicates a traveling path of the work vehicle 1
when performing the lawn mowing operation. The work vehicle 1
travels autonomously. This autonomous traveling is controlled by
the traveling control apparatus 10. The path information
acquisition unit 28 acquires traveling path information that
indicates a traveling path through which the work vehicle 1 has
traveled autonomously. It is preferable that the traveling path is
calculated using position information obtained by a GPS.
The determination unit 29 determines whether or not a current
location is in an area where grass has been mowed, based on the map
and the traveling path information. The map is transferred to the
determination unit 29 from the working field map acquisition unit
27, and path information is transferred to the determination unit
29 from the path information acquisition unit 28. It is favorable
that the determination unit 29 divides the working field in the
transferred map into a plurality of areas, for example.
Furthermore, it is favorable that the determination unit 29
classifies each area into an area where the work vehicle 1 has
traveled and an area where the work vehicle 1 has not traveled,
based on the traveling path information. Furthermore, it is
favorable that the determination unit 29 determines whether or not
the area where the work vehicle 1 is currently present is an area
where grass has been mowed. The result of the determination
performed by the determination unit 29 is transferred to the
aforementioned evaluation unit 25.
The evaluation unit 25 can also evaluate the grass height and the
grass density of lawn grass based on the determination result from
the determination unit 29. That is to say, in the case where the
work vehicle 1 is about to travel in an area for which it is
determined by the determination unit 29 that the lawn mowing
operation has not yet been performed, it is favorable that the
evaluation unit 25 performs the evaluation as illustrated in FIG.
5, and the setting unit 24 sets the height of the mowing blade 54
with respect to the working surface to any of the operating heights
shown in FIG. 5. Also, in the case where the work vehicle 1 is
about to travel in an area for which it is determined by the
determination unit 29 that the lawn mowing operation has already
been performed, it is favorable that the evaluation unit 25
performs an evaluation such that the height of the mowing blade 54
with respect to the working surface is set to an operating height
that does not affect the traveling. It is also possible that the
evaluation unit 25 is configured to evaluate the type of lawn grass
using a captured image, and the setting unit 24 is configured to
set the operating height in accordance with the grass type.
Returning to FIG. 3, each of the load sensors 30 detects a load. In
this embodiment, a pair of load sensors 30 are provided, one on the
front side of the work vehicle 1 relative to the traveling
direction, and the other on the rear side relative to the traveling
direction. In this embodiment, these load sensors 30 are attached
to the later-described bumper members 31. Each of the load sensors
30 detects a pressure that acts on a corresponding one of the
bumper members 31, and transfers the detection result to the
traveling control apparatus 10.
The bumper members 31 are supported by the base frame 21 so as to
at least surround the lawn mowing apparatus 53 and the wheels 2. To
"surround the lawn mowing apparatus 53 and the wheels 2" refers to
a state where the bumper members 31 are located outward of the lawn
mowing apparatus 53 and the wheels 2 as viewed from above the work
vehicle 1. In this embodiment, a pair of bumper members 31 are
provided. One of the bumper members 31 is provided rearward of the
first wheels 2A relative to the traveling direction of the work
vehicle 1, and the other one of the bumper members 31 is provided
forward of the second wheels 2B relative to the traveling direction
of the work vehicle 1. The pair of bumper members 31 are fixed to
the base frame 21.
The bumper members 31 are configured to surround the lawn mowing
apparatus 53 and the wheels 2 even if the height of the unit frame
22 with respect to the base frame 21 is changed. As mentioned
above, the height of the unit frame 22 with respect to the base
frame 21 can be changed by the link frames 23. The bumper members
31 are provided so as to keep a fixed gap between the lawn mowing
apparatus 53 and the working surface even if the aforementioned
height is changed by the link frames 23 such that the lawn mowing
apparatus 53 and the wheels 2 are not exposed, i.e. the lawn mowing
apparatus 53 and the wheels 2 cannot be seen from the front side
and the rear side of the work vehicle 1 relative to the traveling
direction. This configuration can prevent an object other than
grass from being stuck in the lawn mowing apparatus 53, and prevent
the wheels 2 from riding up such an object.
The control unit 32 stops running the lawn mowing apparatus 53 if
any of the load sensors 30 detects a load that is greater than or
equal to a preset value, and causes the wheels 2 to roll in a
direction opposite to the direction in which the wheels 2 were
rolling when the load that is greater than or equal to the preset
value was detected. The result of detection performed by each of
the load sensors 30 is transferred to the control unit 32. If the
detection result transferred from any of the load sensors 30
indicates detection of a load that is greater than or equal to the
preset value, the control unit 32 stops running the lawn mowing
apparatus 53. This configuration can prevent an object that has
applied a pressure to the load sensors 30 from being stuck in the
lawn mowing apparatus 53. Furthermore, the control unit 32 controls
the traveling control apparatus 10 so as to travel in a direction
opposite to the direction in which the work vehicle 1 was traveling
before any of the load sensors 30 detected a load. Thus the work
vehicle 1 travels backward. As a result, the wheels 2 can be
withdrawn from the object that has applied a pressure to the load
sensors 30.
Variations of First Embodiment
In the above-described embodiment, the evaluation unit 25 evaluates
the grass height and the grass density of lawn grass, and the
setting unit 24 sets the operating height in accordance with the
evaluation result from the evaluation unit 25. However, the setting
unit 24 can alternatively be configured to set the operating height
regardless of the evaluation result from the evaluation unit 25. In
this case, the work vehicle 1 may not be provided with the
evaluation unit 25.
In the above-described embodiment, the captured image acquisition
unit 26 acquires a captured image of a working field, and the
evaluation unit 25 evaluates the grass height and grass density of
lawn grass based on the captured image. However, the evaluation
unit 25 can alternatively be configured to evaluate the grass
height and grass density of lawn grass without using a captured
image.
In the above-described embodiment, the working field map
acquisition unit 27 acquires a map that illustrates a working
field, and the path information acquisition unit 28 acquires
traveling path information that indicates a traveling path during
the operation. Also, in the above-described embodiment, the
determination unit 29 determines whether or not the current
location is in an area where grass has already been mown, based on
the map and the traveling path information, and the evaluation unit
25 evaluates the grass height and the grass density of lawn grass
based on the determination result from the determination unit 29.
However, the work vehicle 1 can alternatively be configured to not
include the working field map acquisition unit 27, the path
information acquisition unit 28, and the determination unit 29.
In the above-described embodiment, the load sensors 30 are attached
to the bumper members 31, but the load sensors 30 may alternatively
be attached to members other than the bumper members 31.
In the above-described embodiment, the bumper members 31 are
configured to surround the lawn mowing apparatus 53 and the wheels
2 even if the height of the unit frame 22 with respect to the base
frame 21 is changed. However, a configuration may alternatively be
employed in which the lawn mowing apparatus 53 and the wheels 2 are
exposed from the bumper members 31 if the height of the unit frame
22 with respect to the base frame 21 is changed.
In the above-described embodiment, the control unit 32 stops
running the lawn mowing apparatus 53 if any of the load sensors 30
detects a load that is greater than or equal to a preset value, and
causes the wheels 2 to roll in a direction opposite to the
direction in which the wheels 2 were rolling when the load that is
greater than or equal to the preset value was detected. However, if
any of the load sensors 30 detects a load that is greater than or
equal to the preset value, the control unit 32 can alternatively be
configured to at least either stop running the lawn mowing
apparatus 53 or roll the wheels 2 in a direction opposite to the
direction in which the wheels 2 were rolling when the load that is
greater than or equal to the preset value was detected, or may
alternatively be configured to not stop running the lawn mowing
apparatus 53 and not roll the wheels 2 in the opposite
direction.
In the above-described embodiment, the operation is a lawn mowing
operation, but the operation may alternatively be any other
operation.
Second Embodiment
The second embodiment of the present invention will be described
below.
A work vehicle according to the present invention is configured to
be able to perform an operation smoothly. The work vehicle performs
the operation while traveling autonomously, and the following
description will take a lawn mowing operation as an example of the
operation performed by the work vehicle. Here, "autonomous
traveling" according to this embodiment refers to traveling while
avoiding objects (e.g. obstacles) along a traveling path that is
set based on the output of a device mounted in the work vehicle
(e.g. output of a sensor, an image captured by a camera etc.). Such
a work vehicle corresponds to a so-called autonomous robot.
FIG. 6 is a side view of a work vehicle 101 according to this
embodiment, and FIG. 7 is a plan view of the work vehicle 101. As
shown in FIGS. 6 and 7, the work vehicle 101 includes wheels 102
and a body 103 (an example of a vehicle body). The wheels 102
include first wheels 102A on one end side of the vehicle body in
the vehicle-lengthwise direction, and second wheels 102B on the
other end side in the vehicle-lengthwise direction. A pair of left
and right first wheels 102A and a pair of left and right second
wheels 102B are provided, respectively in the vehicle-widthwise
direction. In this embodiment, the first wheels 102A are provided
on the rear side of the work vehicle 101 relative to the traveling
direction. The first wheels 102A are configured as wheels that are
driven and steered. The first wheels 102A are driven by a
later-described traveling control apparatus 110. The second wheels
102B are provided on the front side of the work vehicle 101
relative to the traveling direction. The second wheels 102B are
configured as so-called caster wheels. With this configuration, if
the left and right first wheels 102A are rolling in the same
direction at the same speed, the work vehicle 101 travels straight.
If the left and right first wheels 102A are rolling in the same
direction at different speeds, the work vehicle 101 is in a state
of being steered toward the side of one of the left and right first
wheels 102A that is rolling at a lower speed. Furthermore, if the
left and right first wheels 102A are rolling in different
directions at the same speed, the work vehicle 101 can rotate on
the spot. Although, in the above description, a pair of left and
right first wheels 102A and a pair of left and right second wheels
102B are provided, respectively in the vehicle-widthwise direction,
this is merely an example. For example, the number of first wheels
102A may differ from the number of second wheels 102B, or the
number of first wheels 102A and the number of second wheels 102B
may be one or three or more, in accordance with the size of the
vehicle body.
The body 103 is provided with a pair of motors 104, which serve as
motive power sources for the first wheels 102A, a battery 105 for
storing electric power and supplying electric power to the motors
104 and electrical devices that the work vehicle 101 has, a
traveling control apparatus 110 for controlling traveling of the
work vehicle 101, and a motor 106 for driving a lawn mowing
apparatus 153 (an example of an operation unit), which has a mowing
blade 154, which is used in lawn mowing. The motor 106 is driven by
electric power supplied by the battery 105.
The body 103 is also provided with a satellite positioning module
199, which is configured as a GNSS module. The satellite
positioning module 199 has a satellite antenna for receiving a GPS
signal or a GNSS signal ("GPS signal" in this embodiment). Note
that the satellite positioning module 199 may include an inertial
navigation module that incorporates a gyro-acceleration sensor
and/or a magnetic direction sensor to complement satellite
navigation. Needless to say, the inertial navigation module may be
provided at location separate from the satellite positioning module
199. A GPS signal acquired by the satellite positioning module 199
is used in aforementioned autonomous traveling of the work vehicle
101.
The lawn mowing apparatus 153 includes a load reduction unit 158
and an operation completion unit 159. The load reduction unit 158
performs an operation for reducing the load of the operation whose
load is greater than a preset load. For example, in the lawn mowing
operation, it is not easy to cut lawn grass to an intended grass
height at a time, and such way of cutting tends to shorten the
lifetime of the mowing blade 154 of the lawn mowing apparatus 153.
For this reason, it is favorable to first cut lawn grass to a grass
height that is greater than the intended grass height, and then
further cut the lawn grass to the intended grass height. In this
embodiment, the load is determined based on the grass height in
order to make it easier to readily understand the operation load.
Accordingly, "an operation for reducing the load of the operation
whose load is greater than a preset load" means an operation to cut
lawn grass to a predetermined grass height if the grass height of
the lawn grass is greater than a preset grass height. Accordingly,
the load reduction unit 158 performs an operation to cut lawn grass
to the predetermined grass height if the grass height lawn grass is
greater than the preset grass height.
Specifically, in this embodiment, a front mowing blade that is
provided in a front portion of the vehicle body relative to the
traveling direction corresponds to the load reduction unit 158.
This front mowing blade is provided at a position higher than the
position of a rear mowing blade, which is the later-described
operation completion unit 159. Thus, the grass height of overgrown
lawn grass can be first cut to the predetermined grass height. As a
result, the subsequent lawn mowing operation can be lessened.
The operation completion unit 159 performs the remainder of the
operation, for which the load reduction unit 158 has reduced the
load. As mentioned above, in this embodiment, the load reduction
unit 158 has performed the operation to cut lawn grass to the
predetermined grass height before the operation completion unit 159
performs the lawn mowing operation. Thus, "the remainder of the
operation, for which the load reduction unit 158 has reduced the
load" means an operation to cut, to an intended grass height, the
lawn grass that has been cut to the predetermined grass height by
the front mowing blade, in the lawn mowing operation. Accordingly,
the operation completion unit 159 performs the operation to cut the
lawn grass that has been cut to the predetermined grass height by
the front mowing blade to the intended grass height, in the lawn
mowing operation. The work vehicle 101 can thus complete the lawn
mowing operation.
Specifically, in this embodiment, the rear mowing blade that is
provided in the rear portion of the vehicle body relative to the
traveling direction corresponds to the operation completion unit
159. This rear mowing blade is provided at a position lower than
the position of the front mowing blade, which is the load reduction
unit 158. Thus, the grass height of lawn grass that has been cut to
the predetermined height by the front mowing blade can be cut to
the intended grass height.
The work vehicle 101 can thus perform the lawn mowing operation
smoothly by cutting lawn grass at separate times. In addition, lawn
grass can be cut neatly.
In this embodiment, the work vehicle 101 is provided with a load
calculation unit 171 forward of the lawn mowing apparatus 153
relative to the traveling direction in the vehicle body. The load
calculation unit 171 calculates the operation load. In this
embodiment, the grass height of lawn grass that is to be cut
corresponds to the operation load. Thus the load calculation unit
171 calculates the grass height of the lawn grass that is to be cut
by the work vehicle 101. This calculation of the grass height can
be performed using a load sensor, for example. Alternatively, the
grass height can be calculated using an infrared sensor or an image
captured by a camera. Here, there is a possibility that the grass
height of lawn grass cannot be calculated appropriately as a result
of the lawn grass being trodden by the wheels 102 of the work
vehicle 101. To appropriately calculate the grass height, in this
embodiment, the load calculation unit 171 is provided forward,
relative to the traveling direction, of the second wheels 102B that
are provided on the front side of the work vehicle 101 relative to
the traveling direction. Accordingly, the load calculation unit 171
is provided forward, relative to the traveling direction, of the
second wheels 102B that are provided on the front side of the work
vehicle 101 relative to the traveling direction, and calculates the
grass height of lawn grass that is to be cut. The result of
calculation performed by the load calculation unit 171 is
transferred to a later-described decision unit 172.
The decision unit 172 decides whether to drive both the load
reduction unit 158 and the operation completion unit 159 or to only
drive the operation completion unit 159, based on the calculation
result from the load calculation unit 171. The calculation result
is transferred to the decision unit 172 from the load calculation
unit 171. For example, if the grass height of lawn grass that is to
be cut exceeds a predetermined value (e.g. the height of the front
mowing blade), the lawn grass is first cut such that the grass
height thereof is the predetermined value by the front mowing
blade, which is the load reduction unit 158. Thereafter, the rear
mowing blade, which is the operation completion unit 159, cuts the
lawn grass to the intended grass height. Thus the lawn mowing
operation can be performed more smoothly than in the case of
cutting lawn grass only using the operation completion unit 159.
With this configuration, if the calculation result transferred from
the load calculation unit 171, i.e. the grass height of the lawn
grass that is to be cut exceeds the predetermined value (e.g. the
height of the front mowing blade), the decision unit 172 decides to
drive both the front mowing blade, which is the load reduction unit
158, and the rear mowing blade, which is the operation completion
unit 159.
On the other hand, for example, if the grass height of the lawn
grass that is to be cut is smaller than or equal to the
predetermined value (e.g. the height of the front mowing blade),
the lawn grass cannot be cut even if the front mowing blade, which
is the load reduction unit 158, is driven. Therefore, the lawn
mowing operation is performed to cut the lawn grass to the intended
grass height only using the rear mowing blade, which is the
operation completion unit 159. With this configuration, if the
calculation result transferred from the load calculation unit 171,
i.e. the grass height of the lawn grass that is to be cut is
smaller than or equal to the predetermined value (e.g. the height
of the front mowing blade), the decision unit 172 decides to only
drive the rear mowing blade, which is the operation completion unit
159. The result of the decision made by the decision unit 172 is
transferred to the lawn mowing apparatus 153, and the lawn mowing
apparatus 153 drives the mowing blade(s) to be driven based on the
decision result from the decision unit 172. Note that the grass
heights of the lawn grass that is to be cut respectively by the
front mowing blade, which is the load reduction unit 158, and the
rear mowing blade, which is the operation completion unit 159, can
be set by the user inputting desired mowing heights using a
terminal.
Also, considering such an operation, completion of the operation
requires some cost. It is preferable that the decision unit 172
calculates the cost required to complete the operation based on at
least one of the time required for the operation that was performed
previously in the same field, the number of times that the battery
105 was charged, and the power consumption required for the
operation, and decides the running state of the lawn mowing
apparatus 153 also using the calculated cost. The operation that
was performed previously in the same field refers to the lawn
mowing operation that was performed previously in the working field
in which the work vehicle 101 is to perform at this time. The
number of times that the battery 105 was charged refers to the
number of times that the battery 105 was charged while the lawn
mowing operation was performed previously in this working field.
Electric power stored in this battery 105 is also used by the work
vehicle 101 to travel. The number of times that the battery 105 is
charged is therefore proportional to the traveling distance of the
work vehicle 101. It is favorable that the power consumption
required for the operation is calculated based on electric power
output by the battery 105. Thus, not only the power consumption by
the lawn mowing apparatus 153 but also the power consumption
required for the work vehicle 101 to travel can be taken into
consideration.
Accordingly, the decision unit 172 calculates a cost needed for the
current lawn mowing operation using at least one of the time
required for the lawn mowing operation that was performed
previously in the working field in which the work vehicle 101 is to
perform the lawn mowing operation at this time, the number of times
that the battery 105 was charged while the lawn mowing operation
was performed previously in this working field, and electric power
that was output by the battery 105, and decides whether to drive
both the front mowing blade, which is the load reduction unit 158,
and the rear mowing blade, which is the operation completion unit
159, or drive only the rear mowing blade, which is the operation
completion unit 159, while also giving consideration to the
calculated cost. Thus the lawn mowing operation can be performed
efficiently.
Variations of Second Embodiment
In the above-described embodiment, the load reduction unit 158 is
provided in the front portion of the vehicle body relative to the
traveling direction, and the operation completion unit 159 is
provided in the rear portion of the vehicle body relative to the
traveling direction. However, as shown in FIG. 8, the operation
completion unit 159 may alternatively be provided in the center
portion of the vehicle body as viewed from above, and the load
reduction unit 158 may alternatively be provided so as to surround
the operation completion unit 159 as viewed from above the vehicle
body. In this case, it is favorable that the operation completion
unit 159 provided in the center portion is a reel or a rotary blade
for fine cutting, which needs to be accurate, and the load
reduction unit 158 provided around the operation completion unit
159 is a flail mower or a clipper mower. With this configuration as
well, the load reduction unit 158 can reduce the load on the
operation completion unit 159, and the operation can be performed
smoothly, similarly to the above-described embodiment.
In the above-described embodiment, the work vehicle 101 has the
load calculation unit 171 for calculating an operation load forward
of the lawn mowing apparatus 153 relative to the traveling
direction in the vehicle body, and has the decision unit 172 for
deciding whether to drive both the load reduction unit 158 and the
operation completion unit 159 or to only drive the operation
completion unit 159, based on the calculation result from the load
calculation unit 171. However, the work vehicle 101 may
alternatively be configured to not include the load calculation
unit 171 and the decision unit 172. In this case, it is favorable
to perform the operation while constantly driving both the load
reduction unit 158 and the operation completion unit 159. Also, the
load calculation unit 171 may alternatively be provided forward of
the lawn mowing apparatus 153 relative to the traveling direction
and rearward of the second wheels 102B. In this case, it is
favorable that the load calculation unit 171 is provided at a
position (e.g. in the center portion of the work vehicle 101
relative to the vehicle width direction) at which lawn grass is not
trodden by the second wheels 102B.
In the above-described embodiment, the decision unit 172 decides
the running state of the lawn mowing apparatus 153 also using the
cost required to complete the operation. However, the decision unit
172 can alternatively be configured to decide the running state of
the lawn mowing apparatus 153 without using the cost required to
complete the operation.
In the above embodiment, the operation is a lawn mowing operation,
but the operation may alternatively be any other operation.
The present invention can be applied to a work vehicle that
performs an operation while traveling autonomously.
* * * * *